Replaceable fluid cartridge including magnetically operable fluid jet devices

ABSTRACT

An ink cartridge for an ink jet printing apparatus wherein ink jets (&#39;&#39;&#39;&#39;Spritzers&#39;&#39;&#39;&#39;) are mounted at the periphery of a rotationally driven disc member and a recording medium is guided past an arcuate portion of the periphery of the disc member at a proximate distance therefrom. The cartridge has the form of a disc and includes mangetostrictive ink jets mounted at the periphery of the disc and an ink reservoir within the disc communicating with the ink jets to supply ink to the ink jets. The ink jets are operable in response to a magnetic field coupled to the ink jets. The ink cartridge is adapted to be removably mounted on a turntable. The turntable includes magnetic field elements coupled to electrical control signals manifesting printing information for inducing a magnetic field in the magnetostrictive ink jets to operate the ink jets in response to the electrical control signals.

[ Feb. 4, 1975 Primary ExaminerJoseph W. Hartary Attorney, Agent..0rFirmE. J. Norton; R. E. Smiley; J. D. Lazar [57] ABSTRACT An inkcartridge for an ink jet printing apparatus wherein ink jets (Spritzers)are mounted at the periphery of a rotationally driven disc member and arecording medium is guided past an arcuate portion of the periphery ofthe disc member at a proximate distance therefrom. The cartridge has theform of a disc and includes mangetostrictive ink jets mounted at theperiphery of the disc and an ink reservoir within the disc communicatingwith the ink jets to supply ink to the ink jets. The ink jets areoperable in response to a magnetic field coupled to the ink jets. Theink cartridge is adapted to be removably mounted on a turntable. Theturntable includes magnetic field elements coupled to electrical controlsignals manifesting printing information for inducing a magnetic fieldin the magnetostrictive ink jets to operate the ink jets in response tothe electrical control signals.

l0 Claims, 4 Drawing Figures United States Patent [1 Fischbeck l lREPLACEABLE FLUID CARTRIDGE INCLUDING MAGNETICALLY OPERABLE FLUID JETDEVICES [75] Inventor: Kenneth Henry Fischbeck, Mercer,

[73] Assignee: RCA Corporation, New York, NY.

[22] Filed: Mar. 29, 1974 [21] Appl. No.: 456,127

[30] Foreign Application Priority Data May 21, 1973 GreatBritain.................... 24139/73 [52] U.S. Cl. 346/140 [51] Int. Cl.G01d 15/18 [58] Field of Search................ 346/140, 75; 197/1 R[56] References Cited UNlTED STATES PATENTS 3,375,528 3/1968 Klavsons et346/l40 3,683,2[2 8/1972 346/140 X 3,823,409 7/]974 346/140 REPLACEABLEFLUID CARTRIDGE INCLUDING MAGNETICALLY OPERABLE FLUID JET DEVICES CROSSREFERENCE TO RELATED APPLICATIONS Of interest are the followingcopending patent applications: Ser. No. 414.756. filed Nov. 12. 1973,entitled Printing Apparatus." by the same inventor as the presentinventor, and assigned to the same assignee as the present assignee;Ser. No. 456,162, filed on Mar. 29. 1974, entitled Fluid Ejection orControl Device. by the same inventor as the present inventor and EricMcPhail Leyton, and assigned to the same assignee as the presentassignee; and Ser. No. 463,996, filed on Apr. 25, 1974, entitled ImageGenerator Having A Plurality Of Marker Units Operated In A PredeterminedSequence To Inhibit The Formation Of Patterns, by the same inventor asthe present inventor, and assigned to the same assignee as the presentassignee.

BACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to the field of ink jet printing apparatus and particularlyrelates to ink jet printing apparatus of the type in which ink jetsmounted at the periphery ofa rotating disc are operated to impinge dropsofink on a recording medium guided past the periphery of the disc.

2. Prior Art Ink jet printing apparatus are well known, wherein ink issupplied to ink jets, at times termed ink spritzers." which are eitherelectrically or magnetically operated to impinge ink on a recordingmedium. In one type of such ink jet printing apparatus a recordingmedium is moved past a stationary array of ink jets as the ink jets areoperated in response to control signals. As an example of this type ofprinting apparatus see FIG. 1 of US. Pat. No. 3,596,275, entitled FluidDrop Recorder," issued to Richard G. Sweet on July 27, 1971. In anothertype of ink jet printing apparatus the ink jets are operated in responseto control signals as the ink jets are moved past a-stationary recordingmedium. For an example of this type of ink jet printing apparatus seeFIG. 7 of the Sweet patent. In one form of the latter type of ink jetprinting apparatus ink jets are mounted at the periphery of a rotatingdisc. As the ink jets are swept past a recording medium which is guidedpast the periphery of the disc, electrical signals, commutated to theink jets through slip rings orthe like, operate the ink jets to impingeink on the recording medium.

In these prior art apparatus the ink supply is remote from the ink jets.As an example of an ink jet printing apparatus having a remotely locatedink supply see US. Pat. No. 3,564,120, entitled Image ConstructionSystem With Arcuately Scanning Drop Generators, issued to Richard P.Taylor on Feb. 16, 1971. Ink jet printing apparatus having remotelylocated ink supplies require relatively complex interconnectingstructure between the ink supply and the ink jets and therefore do notlend themselves to be easily maintained.

In one printing apparatus of the type employing a rotationally drivendisc having ink jets mounted at its periphery, the disc itself containsan ink reservoir which communicates with the ink jets mounted at itsperiphery to supply ink to the ink jets. Such printing apparatus isdescribed in copending US. Pat. application having Ser. No. 414,756,entitled Printing Apparatus," filed by the same inventor as the presentinventor on Nov. 12. 1973 and assigned to the same assignee as thepresent assignee. In the printing apparatus described in saidapplication, the disc is a removable ink cartridge which may be refilledor replaced when the ink is depleted.

Facsimile systems intended for home use and the like will be more indemand as telephonic. cable television and like forms of datatransmission systems become more available in the consumer market. Forsuch applications. printing apparatus of the type described above shouldpreferably have relatively simple maintenance procedures. Therefore.there is a need in the art for ink cartridges for use in ink jetprinting apparatus which may be readily replaced.

SUMMARY OF THE INVENTION According to the invention, an ink cartridge isprovided for an inkjet printing apparatus of the type wherein ink jetsin relative motion to a recording medium are operated in response toelectrical control signals to impinge jets of ink drops on the recordingmedium. The ink cartridge is self contained and requires no electricalor ink supply connections to the printing apparatus and is thereforereadily attached and detached from the printing apparatus. Therefore,the ink jet printer may be readily maintainable.

The ink cartridge includes a housing member adapted to be readily andreplaceably mounted on a support member. The housing member issubstantially hollow defining a cavity serving as an ink reservoir forstoring ink, The ink cartridge also includes a magnetically operable inkjet communicating with the reservoir to be supplied with ink from thereservoir. The magnetically operable ink jet is operable in response toa mag netic field coupled to the magnetically operable ink jet from thesupport member to direct jets of ink from the housing member to therecording medium. The support member is provided with magnetic meanscoupled to the electrical control signals for coupling a magnetic fieldto the magnetically operable ink jet in accordance with the electricalcontrol signals. The housing member and the support member are adaptedto mate to form an efficient magnetic field path between the magneticmeans and the magnetically operable ink jet.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an isometric exploded view ofa printing apparatus embodying the preferred embodiment of the presentinvention.

FIG. 2 is a sectional view taken in the direction of section line 2-2 ofFIG. 1, showing a plan view of the ink cartridge (12) of FIG. 1.

FIG. 3 is a sectional view taken in the direction'of section 33 of FIG.1 showing the ink jet of FIG. 1 in detail.

FIG. 4 is a cross sectional view taken in the direction of section 44 ofFIG. 1 showing a modification to the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the following description ofthe preferred embodiment the same reference numerals in differentfigures correspond to the same element. Concurrent reference to FIGS. 1,2 and 3 will be helpful.

The printing apparatus of FIG. 1 comprises three components: turntable10, ink cartridge 12, and recording medium guide structure 14. Inoperation cartridge 12 is positioned onjturntable from its separatedposition as shown in FIG. I, to an abutting position as shown in FIG. 3.

Cartridge 12 is a removable ink cartridge generally in the form of adisc having a cavity serving as an ink reservoir l6 and ink jets 18mounted at its periphery. The cavity for reservoir 16 extendssubstantially throughout disc 12 and in a preferred embodiment isdivided by segmented cylindrical wall 40 into inner chamber 16a andouter chamber 16b. Inner chamber 160 of reservoir 16 is exposed to inputports 37 of ink jets 18 through apertures in wall 40 to supply ink toink jets 18. Ink from inner chamber 16a reaches outer chamber 16bthrough openings 41 in wall 40. Ink jets 18 extend radi ally outwardinto annular outer chamber 16b of reservoir 16 such that orifice 38 ofink jet 18 is surrounded with ink to prevent the formation of airbubbles during the printing operation, as will be explained later.'Eachink jet 18 is positioned in-the periphery of cartridge 12 to eject inkradially outward through a corresponding output orifice 42 in the outerwall of cartridge 12 when operated. Ink jets 18 may be any suitable typeof magnetically operable ink jet, such as a magnetostrictive type of inkjet, and are preferably of the magnetostrictive type of ink jetdescribed in copending United States patent application having Ser. No.67,164, entitled Fluid Ejection or Control Device, filed by K. H.Fischbeck and E. M. Leyton on Mar. 29, I974, and assigned to the sameassignee as the present invention.

Cartridge 12 is arranged to be coaxially mounted on turntable 10 in sucha manner that each of the U- shaped magnetic field pole pieces 20mounted on turntable 10 are in longitudinal alignment with a respectiveset of magnetic field pole pieces or elements 22a and 22b of ink jets18, as shown in FIG. 3. Cartridge 12 is provided with keying structureso that cartridge 12 mates with turntable 10 in a registered manner andprevents slipping. Cartridge 12 is locked in position and thus to beheld in non-slip contact with turntable in any suitable mannerincluding, for example, a press fit connection, magnetic connectors orthe like, not shown, which permits cartridge 12 to be readily removedfrom and replaced on turntable 10.

When a current is provided to flow through a coil 24, wound about eachpole piece 20, a magnetic field is induced in a respective pole piece20, which is coupled to a respective set of magnetic field pieces 22aand 22b. In response to this magnetic field, ink jets 18 operate toeject ink radially outwardly in a manner known in the art.

Although pole pieces 20 are shown as having a U- shape, it should beappreciated that they may have any other suitable shape.

Turntable 10 is fixedly mounted on shaft 26 which, in turn, isrotationally driven by means, not shown. As shaft 26 is rotated, inkjets 18 are rotatably driven past a recording medium 26 which issuitably guided past the periphery of an arcuate portion of disc 14 at aproximate distance therefrom by guide member 28.

Cartridge 12 may be of'the expendably replaceable type that is meant tobe discarded after the ink therein is depleted or cartridge 12 may be ofthe refillable type having provisions for being refilled with ink afterthe ink therein is depleted. Cartridge 12 may be formed by any suitablematerial having sufficient strength and rigidity to withstand thecentrifugal forces to which it is subjected when rotated on turntable10. An inexpensive, nonporous and rigid plastic material such as apolyethylene plastic is particularly appropriate if cartridge 12 is toserve as the disposable type, if not as a refillable type.

Control leads 30 carry electrical control signals manifestingsynchronization information, used to synchronize the operation of inkjets 18 with the movement of recording medium 27, as well as printinginformation used to control the intensity'and/or spacing of the inkdrops produced by ink jets 18. The electrical control signals carried bycontrol leads 30 are commutated to shaft 26 by any suitable means suchas slip rings or electro optical transducers from a control unit, notshown, which generates these signals to operate ink jets 18 as they areswept past recording medium 26 as is known in the art. Another portion(not shown) of the control unit of the printing apparatus is arranged tomaintain the speed of shaft 26 in synchronism with the motion ofrecording medium 27 in a manner as is well known in the art.

As stated before, ink jets 18 arepreferably of the type described incopending U.S. application having Ser. No. 456,l62, filed on Mar. 29,1974, entitled Fluid Ejection or .Control Device. Briefly, the preferredink jets 18 are formed by a magnetostrictive tube .32 (FIG. 3) having agenerally elliptical cross section 'tube 32 and spans the major axis ofthe generally elliptical cross section of tube 32. Magnetostrictive tube32 is adapted to contract circumferentially in response to azimuthal orcircumferential magnetic field 36a. Lateral member 34 is adapted toexpand laterally in the direction of span in response to a lateralmagnetic field 36b. Azimuthal magnetic fields 36a and lateral magneticfield 36b are generated by the magnetic field induced in the magneticcore formed by the field pieces 22a and 22b of cartridge 12 and fieldpiece 20 of turn table 10 when a current flows through coil 24. vThecurrent may, for example, be a pulse train being frequency modulated oramplitude modulated or both; the modulation manifesting print controlinformation respectively controlling the spacing, size or both of theink drops impinged on recording medium 27. The end of tube 32 directedradially outwardly is tapered to a nozzle terminating in an outletorifice 38. When current flows through coil 24, the cross section areaof tube 32 of ink jet 18 undergoes a geometric distortion in response tothe magnetic action thereby causing a jet of ink to be ejected fromorifice 38 and through orifice 42.

The efficiency of a type of ink jet such as ink jet 18 is generallydependent on the magnitude of the magpath with a minimum gap in themagnetic circuit as well known in the art.

In a preferred embodiment, reservoir 16 is divided into an inner chamber16a and an outer chamber 16b by cylindrical wall 40 to form what may betermed a fluidic rectifier which functions to prevent air bubbles fromdeveloping during operation causing ink jets 18 to malfunction orotherwise perform erratically. To achieve this action, ink jets 18 aremounted on wall 40 in axial alignment with output orifices 42 ofcartridge 12. The nozzle end of ink jets 18 extends radially out wardlyinto outer chamber 16b while the input open end ofink jets 18 are openor exposed to inner chamber 16a to receive and thereby be supplied withthe ink from inner chamber 160. Wall 40 is provided with a plurality ofaccess openings 41 so that ink within inner chamber 16a may readily flowout to outer chamber 16 and surround orifice 38 of ink jet 18 with ink.ln operations, when a jet of ink is ejected from ink jet 18 throughorifice 42 of cartridge 12, the ink in outer chamber 16!; surroundingorifice 38 fills the vacuated space created by the jet of ink therebyinhibiting the formation of air bubbles in ink jet 18.

As is known in the art, fluidic rectifiers are imperfect and, althoughthey mitigate the problem, they generally do not entirely prevent airbubbles to a degree necessary in some printing applications. It shouldbe appreciated by those skilled in the art that the adverse effect ofair bubbles on the reliable and continuous operation of ink jets 18 willbe considerably diminished because of the advantageous utilization of aninherent pressure gradient established in the ink within reservoir 16 bythe centrifugal forces acting on the ink as cartridge 12 is rotationallydriven by turntable 10. That is, since the pressure is greater at theperiphery of reservoir 16 than it is near the center of reservoir 16 dueto the centrifu gal force acting on the ink within reservoir 16, anybubbles that may be formed by the operation of ink jets 18 are urged tothe center of reservoir 16 and away from ink jets 18. Thus, the inherentpressure gradient due to centrifugal force set up within reservoir 16tends to prevent bubbles from being developed in the jet l8.

Notwithstanding the advantages of inhibiting the formation of airbubbles by the centrifugal action causing the inherent pressure gradientdescribed above, a cartridge 12 having rigid walls that is sealed fromthe ambient except for the apertures established through the ink jets18, will tend to develop a partial vacuum that will thereby inhibit thedischarge flow of ink since, the centrifugal force is not great enoughto cause the ink to be ejected. This action is well known in the art andmay be termed for the present description as the tendency to create avoid." The pressure in such a void is low, and in some cases, approachesthat of vacuum pressure. As ink is depleted more and more, theincreasingly lowered pressure tends to retard the flow of ink to inkjets 18. FIG. 4 is a cross sectional view taken in the direction ofsection 44 of FIG. 1 showing a modification of ink cartridge 12according to the invention wherein means are provided so that theambient pressure outside of ink cartridge 12 can act on ink withinreservoir 16 to counteract the retarding effect of the low pressurevoid. Top surface portion 44 of cartridge 12 is provided with aplurality of orifices 46 serving as vents communicating withthe-interior of the cartridge to allow the pressure outside cartridge 12to act on the ink within reservoir 16. To prevent the ink from leakingor spilling from cartridge 12, membrance 48, formed of any suitablematerial such as a flexible plastic material, is provided to cover theink within reservoir 16. As the ink is depleted through orifices 38 ofjets 18, the ambient pressure external to cartridge 12 acts on membrance48 forcing it downward (as indicated in phantom) to thereby urge the inkradially outward toward jets 18. Top surface portion 44 of cartridge 12may be eliminated as desired.

It will further be appreciated that to the extent air bubbles areremoved from ink jets 18 by the inherent pressure gradient withincartridge 12 when rotationally driven by turntable 10, a separatefluidic rectifier structure to prevent malfunction due to the presenceof air bubbles may not be required, and therefore, outer chamber 16b maynot be required.

In overall operation of the apparatus, ink cartridge 12 is placed onturntable 10 locating the sets of field pieces 22a and 22b of inkcartridge 12 in alignment with and at a proximate vertical distance fromrespective field pieces 20 of turntable 10. Turntable 10 is rotationallydriven. As ink jets 18 are periodically swept past recording medium 27,current control signals manifesting print control information such asthe spacing of or the size of the ink drops to be deposited on recordingmedium are conducted to respective coils 24. ln response to thesecurrent control signals, magnetic fields are induced in the magneticfield paths formed by respective field pieces 22a, 22b and 20 therebyoperating respective ink jets 18 to impinge jets of ink or ink drops onrecording medium 27 in accordance with the current control signals. Whenthe ink in cartridge 12 is depleted, cartridge 12 is removed forrefilling or entirely replaced.

It will be appreciated by those skilled in the art that although theinvention is described in terms of an embodiment useful in an ink jetprinting apparatus, the scope of the invention is not limited to theembodiment described. Therefore, it should now be understood that inaccordance with the invention a replaceable fluid cartridge is providedwhich includes a reservoir for fluid and a magnetically operable 'fluidmetering device for controlling the flow of fluid into and out of thereservoir. The cartridge is adapted to mate with a support structure,such as a turn table or the like, which includes means for generating amagnetic field to control the operation of the magnetically operablefluid metering device.

What is claimed is:

1. An ink cartridge for an ink jet printing apparatus of the typewherein ink jets in relative motion to a recording medium are operatedin response to electrical control signals to deposit drops of ink on therecording 'medium, comprising:

a housing member including a cavity extending substantially throughoutsaid housing member, said cavity forming an ink reservoir for storingink within said housing member, said housing member being adapted to bereplaceably mounted on a support member; and

a magnetically operable ink jet mounted on said housing member andcommunicating with said reservoir to be supplied with ink from saidreservoir for directing jets of ink outwardly from said housing memberand on to said recording medium, said magnetically operable ink jetsbeing operable in response to a magnetic field coupled to saidmagnetically operable ink jets from the support member;

said support member including magnetic means coupled to said electricalcontrol signals for coupling said magnetic field to said magneticallyoperable ink jet in response to said electrical control signals;

said housing member and said support member being adapted to mate toform a magnetic field path between said magnetic means and saidmagnetically operable ink jet.

2. The apparatus recited in claim 1 wherein said support member isdriven to move the ink jets past said recording medium.

3. An ink cartridge for an ink jet printing apparatus of the typewherein ink jets mounted on a rotationally driven member are operated asthey are driven past a recording member which is guided past therotationally driven member, comprising:

a disc member adapted to be removably and coaxially mounted on aturntable adapted to rotationally drive said disc member about its axis,said disc member including a cavity extending substantially throughoutsaid disc member, said cavity forming an ink reservoir for storing inkwithin said disc member;

a magnetically operable ink jet mounted at the periphery of said discmember and communicating with said reservoirto be supplied with ink fromsaid reservoir for directingjets of ink drops radially outward from saiddisc on to said recording medium, said magnetically operable ink jetsbeing operable in response to a magnetic field coupled to saidmagnetically operable ink jet from said turntable; and

said turntable including magnetic means coupled to said electricalcontrol signals for coupling said magnetic field to said magneticallyoperable ink jet in response to said electrical control signals;

said disc member and said support member being adapted to mate to form amagnetic field path between said magnetic means and said magnetically Ioperable ink jet.

4. A printing apparatus wherein ink is deposited on to a recordingmedium in response to electrical control signals, comprising:

a shaft;

means for rotationally driving said shaft about its axis; turntablecoaxially mounted on said shaft to be rotationally driven by said shaft;disc member removably and coaxially mounted on said turntable to berotationally driven by said turntable said disc member being arranged toserve as a replaceable ink cartridge wherein said disc member includes amagnetically operable ink jet mounted at the periphery of said discmember for directing jets of ink radially outward from said disc, acavity extending substantially throughout said disc and locatedgenerally radially inward from said magnetically operable ink jet, saidcavity forming an ink reservoir for storing said ink within said discmember and adapted to supply ink to said magnetically operable ink jet,said magnetically operable ink jet being operable in response to amagnetic field coupled to said magnetically operable ink jet from saidturntable said turntable including magnetic means coupled to saidelectrical control signals for coupling said magnetic field to saidmagnetically operable ink jet in response to said electrical controlsignals;

said disc member and said turntable being adapted to mate to form amagnetic field path between said magnetic means and said magneticallyoperable ink jets; and

means'for guiding said recording medium past the periphery of said discmember.

5. The printing apparatus recited in claim 4 wherein said magneticallyoperable ink jet is of the magnetostrictive type.

6. The printing apparatus recited in claim 5 wherein said magneticallyoperable ink jet comprises:

a tube adapted to channel the flow of said ink having an input at oneend for receiving said fluid from said reservoir and a nozzle at theother end for expelling fluid from said tube;

a lateral member located within said tube, disposed along the axis ofsaid tube and spanning between opposite wall portions of said tube;

said tube and said lateral member forming a passageway for fluid, saidpassageway having a crosssection comprising an arcuate section, formedfrom said tube, and a straight line section, formed from said lateralmember, spanning said arcuate section; v

said tube being formed of a magnetostrictive material adapted so thatsaid arcuate section contracts circumferentially in response to amagnetic field passing circumferentially through said arcuate section;

said lateral member being adapted so that said a straight line sectionexpands laterally in the direction of span in response to a magneticfield passing laterally through said straight line section in thedirection of span;

said arcuate section and said straight line section being arranged toform a'closed loop magnetic path;

magnetic pole pieces having opposite polarities located at oppositesides of said tube and adapted to simultaneously induce a magnetic fieldcircumferentially through said arcuate section and laterally throughsaid straight linesection in response to said control signal;

said cross-section of said tube becoming geometrically distorted inresponse to said control signal, said volume of said tube decreasing asa result of said geometric distortion of said cross-section, wherebysaid jets of ink drops areejected from said jet.

7. The printing apparatus recited in claim 6 wherein said means forcoupling said magnetic field to said ink jet includes a magnetic coreadapted to mate proximately with said magnetic field pieces and a coilcoupled to said electrical control signals wound around said core.

8. The printing apparatus recited in claim 4 wherein said cavity isarranged to serve as a fluidic rectifier and includes inner and outerchambers separated by a cylindrical wall, said magnetically operable inkjets being mounted on said wall, said periphery of said disc includingan orifice opposite said magnetically operable ink jet through whichsaid jets of ink are ejected, said outer chamber communicating with saidinner chamber so that ink within said inner chamber is supplied to saidventing means for equalizing the pressure in said cavity to that of theambient pressure outside of said disc.

10. The apparatus according to claim 9 further in- 5 eluding a flexiblemembrance in said cavity.

1. An ink cartridge for an ink jet printing apparatus of the typewherein ink jets in relative motion to a recording medium are operatedin response to electrical control signals to deposit drops of ink on therecording medium, comprising: a housing member including a cavityextending substantially throughout said housing member, said cavityforming an ink reservoir for storing ink within said housing member,said housing member being adapted to be replaceably mounted on a supportmember; and a magnetically operable ink jet mounted on said housingmember and communicating with said reservoir to be supplied with inkfrom said reservoir for directing jets of ink outwardly from saidhousing member and on to said recording medium, said magneticallyoperable ink jets being operable in response to a magnetic field coupledto said magnetically operable ink jets from the support member; saidsupport member including magnetic means coupled to said electricalcontrol signals for coupling said magnetic field to said magneticallyoperable ink jet in response to said electrical control signals; saidhousing member and said support member being adapted to mate to form amagnetic field path between said magnetic means and said magneticallyoperable ink jet.
 2. The apparatus recited in claim 1 wherein saidsupport member is driven to move the ink jets past said recordingmedium.
 3. An ink cartridge for an ink jet printing apparatus of thetype wherein ink jets mounted on a rotationally driven member areoperated as they are driven past a recording member which is guided pastthe rotationally driven member, comprising: a disc member adapted to beremovably and coaxially mounted on a turntable adapted to rotationallydrive said disc member about its axis, said disc member including acavity extending substantially throughout said disc member, said cavityforming an ink reservoir for storing ink within said disc member; amagnetically operable ink jet mounted at the periphery of said discmember and communicating with said reservoir to be supplied with inkfrom said reservoir for directing jets of ink drops radially outwardfrom said disc on to said recording medium, said magnetically operableink jets being operable in response to a magnetic field coupled to saidmagnetically operable ink jet from said turntable; and said turntableincluding magnetic means coupled to said electrical control signals forcoupling said magnetic field to said magnetically operable ink jet inresponse to said electrical control signals; said disc member and saidsupport member being adapted to mate to form a magnetic field pathbetween said magnetic means and said magnetically operable ink jet.
 4. Aprinting apparatus wherein ink is deposited on to a recording medium inresponse to electrical control signals, comprising: a shaft; means forrotationally driving said shaft about its axis; a turntable coaxiallymounted on said shaft to be rotationally driven by said shaft; a discmember removably and coaxially mounted on said turntable to berotationally driven by said turntable said disc member being arranged toserve as a replaceable ink cartridge wherein said disc member includes amagnetically operable ink jet mounted at the periphery of said discmember for directing jets of ink radially outward from said disc, acavity extending substantially throughout said disc and locatedgenerally radially inward from said magnetically operable ink jet, saidcavity forming an ink reservoir for storing said ink within said discmember and adapted to supply ink to said magnetically operable ink jet,said magnetically operable ink jet being operable in response to amagnetic field coupled to said magnetically operable ink jet from saidturntable said turntable including magnetic means coupled to saidelectrical control signals for coupling said magnetic field to saidmagnetically operable ink jet in response to said electrical controlsignals; said disc member and said turntable being adapted to mate toform a magnetic field path between said magnetic means and saidmagnetically operable ink jets; and means for guiding said recordingmedium past the periphery of said disc member.
 5. The printing apparatusrecited in claim 4 wherein said magnetically operable ink jet is of themagnetostrictive type.
 6. The printing apparatus recited in claim 5wherein said magnetically operable ink jet comprises: a tube adapted tochannel the flow of said ink having an input at one end for receivingsaid fluid from said reservoir and a nozzle at the other end forexpelling fluid from said tube; a lateral member located within saidtube, disposed along the axis of said tube and spanning between oppositewall portions of said tube; said tube and said lateral member forming apassageway for fluid, said passageway having a cross-section comprisingan arcuate section, formed from said tube, and a straight line section,formed from said lateral member, spanning said arcuate section; saidtube being formed of a magnetostrictive material adapted so that saidarcuate section contracts circumferentially in response to a magneticfield passing circumferentially through said arcuate section; saidlateral member being adapted so that said straight line section expandslaterally in the direction of span in response to a magnetic fieldpassing laterally through said straight line section in the direction ofspan; said arcuate section and said straight line section being arrangedto form a closed loop magnetic path; magnetic pole pieces havingopposite polarities located at opposite sides of said tube and adaptedto simultaneously induce a magnetic field circumferentially through saidarcuate section and laterally through said straight line section inresponse to said control signal; said cross-section of said tubebecoming geometrically distorted in response to said control signal,said volume of said tube decreasing as a result of said geometricdistortion of said cross-section, whereby said jets of ink drops areejected from said jet.
 7. The printing apparatus recited in claim 6wherein said means for coupling said magnetic field to said ink jetincludes a magnetic core adapted to mate proximately with said magneticfield pieces and a coil coupled to said electrical control signals woundaround said core.
 8. The printing apparatus recited in claim 4 whereinsaid cavity is arranged to serve as a fluidic rectifier and includesinner and outer chambers separated by a cylindrical wall, saidmagnetically operable ink jets being mounted on said wall, saidperiphery of said disc including an orifice opposite said magneticallyoperable ink jet through which said jets of ink are ejected, said outerchamber communicating with said inner chamber so that ink within saidinner chamber is supplied to said outer chaMber, said outer chamberbeing adapted to surround the output orifice of said magneticallyoperable ink jet with ink to inhibit the formation of air bubbles as inkis ejected from said magnetically operable ink jet.
 9. The printingapparatus recited in claim 4 including venting means for equalizing thepressure in said cavity to that of the ambient pressure outside of saiddisc.
 10. The apparatus according to claim 9 further including aflexible membrance in said cavity.